A winning double for Craig Williams at Flemington has put him in the driver's seat to claim a sixth Melbourne jockeys' premiership.

Williams entered Saturday's meeting tied with apprentice Beau Mertens on 72 winners for the season.

With a strong book of rides, Williams scored aboard $1.40 favourite Anchor Bid in the Byerley Handicap before winning on $2.05 top pick Portman in the Murray Cox Handicap.

The premiership battle with Mertens, who was winless for the second consecutive meeting, continues at Sandown on Wednesday and concludes at Caulfield next Saturday.

Williams said he was delighted to post Saturday's double and knows he's in a good position heading into the final two meetings of the season.

But he also knows Mertens will fight hard to the finish.

"There are 17 races left for the season and the premiership is not over and done with yet," Williams said.

"It's great to get the double today and to be in front but there's still a lot of hard work to be done."

Williams rode a winning double at the corresponding Flemington meeting last year before going on to win his fifth premiership.